[Equest-users] FW: Question about Solar Loads in eQUEST

Keith Swartz kswartz at ecw.org
Mon Feb 9 07:47:18 PST 2009


Vikram,

It seems to me that your test building just has a lot of thermal mass. That would explain the thermal lag and also the small temperature swings during the day. The sunshine first heats the floor, walls, furniture, etc., which does not heat the room air very much right away. After the sun goes down the stored heat in the floor, etc. is released and warms up the room air late into the night.

_____________________
Keith Swartz, P.E., LEED AP
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Energy Center of Wisconsin
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Fax: 608.238.0523
Email: kswartz at ecw.org<mailto:kswartz at ecw.org>
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________________________________
From: Vikram Sami [mailto:VSami at lasarchitect.com]
Sent: Sunday, February 08, 2009 8:19 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Question about Solar Loads in eQUEST


I have a question about how eQUEST calculates solar heat gain. I have been playing around with a little test building - 50' (E-W axis)x100' (N-S axis). The glass type is 2209 from the glazing library, and Walls are R10 and roof R20 (simplified).  I have the building set up with no HVAC system or lights, and a 24/7 equipment load of .25w/sf and 400sf/person occupants.

I also set up hourly reporting for the following:

 1.  space temps

 1.  Building Heating & Cooling loads

 1.  Building cooling load from solar radiation through windows (this is in the building loads option)
So far so good. The matrix below is an average temperature reading for the 21st day of each month. Needless to say, I was really surprised at the lack of diurnal variation in the temperatures.
HR

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

1

59

75

74

94

97

103

103

106

95

88

79

52

2

59

75

74

94

96

102

103

105

95

88

79

52

3

58

75

73

93

96

102

102

105

95

87

79

52

4

58

75

73

93

96

101

102

104

94

87

78

51

5

57

75

72

93

95

101

102

104

94

87

78

51

6

57

74

72

92

95

101

101

104

94

87

78

51

7

57

74

72

92

96

101

101

104

93

87

77

50

8

56

74

74

92

97

101

101

106

94

87

77

50

9

59

74

76

94

99

101

101

107

94

87

77

50

10

62

75

78

95

100

102

102

108

94

88

78

51

11

64

75

79

96

101

103

102

109

96

89

78

52

12

64

75

80

98

102

103

103

109

97

90

79

52

13

65

75

80

98

102

104

103

109

98

91

81

53

14

66

76

80

99

102

105

104

109

99

92

82

54

15

67

77

82

98

103

105

104

110

100

93

83

55

16

68

77

83

98

104

105

104

110

101

94

84

56

17

69

76

84

98

105

105

104

110

101

94

83

56

18

68

76

84

97

103

105

103

110

100

92

82

54

19

66

75

83

96

102

105

102

108

99

91

81

53

20

65

75

81

95

102

103

102

107

98

91

80

52

21

65

74

80

94

101

103

101

107

97

90

80

52

22

65

74

80

93

101

102

101

106

97

90

79

51

23

64

74

79

92

100

101

100

106

96

89

79

51

24

64

74

79

91

99

101

100

105

96

89

79

51


Below are the values for building solar cooling load(March 21st) , and I was surprised to see pretty high numbers way into the night. Whats going on here? What am I missing? Is the program really calculating solar heat gain at night?

Any insight would be appreciated.
March 21st

Building Sensible
 Heating Load

Building Solar Cooling Load

Building Cooling Load

1

-8365

9893

2873

2

-13659

9130

622

3

-19593

0

0

4

-25131

0

0

5

-30065

0

0

6

-31552

0

0

7

-32832

0

0

8

0

35775

19007

9

0

52932

66006

10

0

63286

88046

11

0

67255

102730

12

0

66069

100438

13

0

64668

91534

14

0

66645

103475

15

0

73743

125298

16

0

83476

141834

17

0

90939

149947

18

0

91079

134182

19

0

76486

95414

20

0

62291

59587

21

0

55129

43966

22

0

49127

32469

23

0

44022

23887

24

-1310

30091

13995








Vikram Sami, LEED AP

Direct Phone 404-253-1466 | Direct Fax 404-253-1366



LORD, AECK & SARGENT ARCHITECTURE

Responsive Design * Technological Expertise * Exceptional Service

www.lordaecksargent.com
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